/* const fs = require('fs') // file system
fs.readFile('./a.txt', {encoding: 'utf-8'}, (err, data) => {
  console.log(data);
}) */

// require('./js/a')
// 全部引入
/* const obj = require('./js/b')

console.log(obj); */

// 按需引入
/* const { a, b } = require('./js/b')
console.log(a, b); */

// 引入默认值
const str = require('./js/c');
console.log(str);